A pipe joint disclosed by Patent Literature 1 includes first and second pipe joint members of synthetic resin, an annular gasket of synthetic resin having a square section and interposed at a butting part between the joint members, an annular male screw member fitted in the second joint member, and a cap nut fitted from the side of the first joint member and screwed on the male screw member. The joint members have a prescribed equal inner diameter over their entire lengths. The joint members each include a large thickness portion positioned close to the butting part, a small thickness portion positioned away from the butting part, and a flange portion provided at the butting end of the large thickness portion. As the cap nut is fastened onto the male screw member, the male screw member presses the flange portion of the second joint member axially inwardly, and the cap nut presses the flange portion of the first joint member axially inwardly, so that the joint members are closely contacted with each other through the gasket.
In the pipe joint disclosed by Patent Literature 1, the flange portions of the first and second pipe joint members must be formed for example by cutting. In this way, the first and second pipe joint members must be subjected to processing particularly for these members, and therefore pipes connected to the first and second pipe joint members are preferably discrete members from the first and second pipe joint members. However, the pipes and the pipe joint members must be welded together particularly if high pressure fluid is to be passed through the pipe joint members, which would complicate the operation of connecting the pipes.